inet_ntop.c

ソースコードを見る。

関数
static const char *	inet_ntop4 (const unsigned char *src, char *dst, size_t size)
static const char *	inet_ntop6 (const unsigned char *src, char *dst, size_t size)
const char *	inet_ntop (int af, const void *src, char *dst, size_t size)

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関数

static const char * inet_ntop4	(	const unsigned char *	src,
		char *	dst,
		size_t	size
	)			[static]

inet_ntop.c の 74 行で定義されています。

参照先 errno・sprintf().

参照元 inet_ntop().

{
        static const char *fmt = "%u.%u.%u.%u";
        char tmp[sizeof "255.255.255.255"];

        if ((size_t)sprintf(tmp, fmt, src[0], src[1], src[2], src[3]) >= size)
        {
                errno = ENOSPC;
                return (NULL);
        }
        strcpy(dst, tmp);

        return (dst);
}

static const char * inet_ntop6	(	const unsigned char *	src,
		char *	dst,
		size_t	size
	)			[static]

inet_ntop.c の 97 行で定義されています。

参照元 inet_ntop().

{
        /*
         * Note that int32_t and int16_t need only be "at least" large enough
         * to contain a value of the specified size.  On some systems, like
         * Crays, there is no such thing as an integer variable with 16 bits.
         * Keep this in mind if you think this function should have been coded
         * to use pointer overlays.  All the world's not a VAX.
         */
        char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
        struct { int base, len; } best, cur;
        unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
        int i;

        /*
         * Preprocess:
         *      Copy the input (bytewise) array into a wordwise array.
         *      Find the longest run of 0x00's in src[] for :: shorthanding.
         */
        memset(words, '\0', sizeof words);
        for (i = 0; i < NS_IN6ADDRSZ; i++)
                words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
        best.base = -1;
        cur.base = -1;
        for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
                if (words[i] == 0) {
                        if (cur.base == -1)
                                cur.base = i, cur.len = 1;
                        else
                                cur.len++;
                } else {
                        if (cur.base != -1) {
                                if (best.base == -1 || cur.len > best.len)
                                        best = cur;
                                cur.base = -1;
                        }
                }
        }
        if (cur.base != -1) {
                if (best.base == -1 || cur.len > best.len)
                        best = cur;
        }
        if (best.base != -1 && best.len < 2)
                best.base = -1;

        /*
         * Format the result.
         */
        tp = tmp;
        for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
                /* Are we inside the best run of 0x00's? */
                if (best.base != -1 && i >= best.base &&
                    i < (best.base + best.len)) {
                        if (i == best.base)
                                *tp++ = ':';
                        continue;
                }
                /* Are we following an initial run of 0x00s or any real hex? */
                if (i != 0)
                        *tp++ = ':';
                /* Is this address an encapsulated IPv4? */
                if (i == 6 && best.base == 0 &&
                    (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
                        if (!inet_ntop4(src+12, tp,
                                        sizeof tmp - (tp - tmp)))
                                return (NULL);
                        tp += strlen(tp);
                        break;
                }
                tp += sprintf(tp, "%x", words[i]);
        }
        /* Was it a trailing run of 0x00's? */
        if (best.base != -1 && (best.base + best.len) ==
            (NS_IN6ADDRSZ / NS_INT16SZ))
                *tp++ = ':';
        *tp++ = '\0';

        /*
         * Check for overflow, copy, and we're done.
         */
        if ((size_t)(tp - tmp) > size) {
                errno = ENOSPC;
                return (NULL);
        }
        strcpy(dst, tmp);
        return (dst);
}

const char* inet_ntop	(	int	af,
		const void *	src,
		char *	dst,
		size_t	size
	)

inet_ntop.c の 46 行で定義されています。

参照先 errno・inet_ntop4()・inet_ntop6().

参照元 getnameinfo().

{
        switch (af) {
        case AF_INET:
                return (inet_ntop4(src, dst, size));
#ifdef AF_INET6
        case AF_INET6:
                return (inet_ntop6(src, dst, size));
#endif
        default:
                errno = EAFNOSUPPORT;
                return (NULL);
        }
        /* NOTREACHED */
}

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